A sectored mould generally has two lateral shells for moulding the sidewalls of the tire, and several peripheral sectors, situated between the shells, for moulding the tread of the tire. The tread is moulded more precisely by linings comprising patterns of the tire. These moulding linings are attached and fastened to the inner face of each sector or formed integrally.
During vulcanization, with the green blank of the future tire being firmly pressed and held against the mould, said green blank is subjected to certain pressure and temperature conditions which cause the raw rubber compound to become fluid. Thus, very good sealing of the mould is necessary to avoid the appearance of flash on the tire during curing.
However, in practice, the closure of a vulcanizing mould over a plurality of faces at the same time and with a clearance between different parts of less than 0.03 mm is difficult to achieve on the sectored moulds known from the prior art.
One solution to this problem is proposed by the patent EP0522374. That patent proposes a sectored mould that also comprises lateral ring segments fastened to the sectors. In the closed position of the mould, the sectors are in contact with one another via said segments, which also ensure contact between the sectors and the shells. Thus, by exerting elastic compression on the ring segments by pressing them against one another, the clearance between parts can be reduced, this then reducing the risk of the appearance of flash on the tire.
However, the ring segments have to be manufactured separately, fitted and then fastened to each sector, thereby making the manufacture of the mould more complex. Moreover, this solution requires a large number of additional parts comprising the ring segments and the fastening parts, thereby making it expensive to manufacture the mould.